Catalytic degradation of acetaminophen by C and O co-doped graphitic carbon Nitride: Peroxymonosulfate vs. Peroxydisulfate

Though peroxymonosulfate (PMS) and peroxydisulfate (PDS) have been studied for catalytic degradation of organic pollutants, much to be elucidated for the differences of them. In this study, they were used in acetaminophen (ACT) removal, activated by C and O co-doped graphitic carbon nitride (CN) (COCN), and the performance and mechanisms were comparatively investigated. COCN had more defects and O-containing groups, and showed higher reactivity than O-doped CN (OCN). COCN/PMS was greatly superior to COCN/PDS in ACT removal, because of faster and more adsorption of PMS than PDS onto COCN. 1O2 generation on C = O and electron transfer were dominantly responsible in both systems, but were much more and faster in COCN/PMS than in COCN/PDS. In addition, O2− was involved in 1O2 generation only in COCN/PMS, while persistent free radicals in COCN were reacted only with PDS. Both systems share similar ACT degradation pathways and changes in COCN properties after uses. The potential in practical applications was verified by the performance in the presence of co-existing ions and natural organic matter, and in real wastewater. It is believed that this study would provide new insights into the differences between PMS and PDS, in the degradation of organic pollutants using carbonaceous materials.